The invention concerns an ultrasonic transducer dipole, in which an electromechanical transducer motor assembly and two symmetrical pads resonate and excite a resonant assembly of two pipes, coupled to two reentrant matching pads at their ends, especially suitable for performing ultrasonic cleaning tasks.
Among the cleaning applications of the invention, one can mention the ultrasonic cleaning of pieces submerged in a liquid medium, without the need to use a stainless steel vat; ultrasonic cleaning of the inside of receptacles holding a liquid, such as tanks, basins and containers.
It can also be used in acoustic applications, where it is desired to transmit the ultrasound to a gaseous medium.
In ultrasonic transducers, the best coupling to the load is sought with the highest possible yield and lowest cost of production, installation and maintenance.
The most common ultrasonic transducers for applications in liquid media are those which in general are coupled glued to the walls of the stainless vat containing them, and the electromechanical transducer commonly used consists of one or more piezoelectric disks compressed between two pads of materials and sizes suitable for optimizing it.
For low power and service applications, the ceramic crystal is directly glued to the receptacle, that is, without the use of pads and matching pads.
Due to the fact that these ultrasonic transducers are glued, are coupled to a small area of the receptacles and therefore dissipate a good part of the energy in the air, not a great deal of power can be handled in them.
On the other hand, on making the receptacle to which they are adhere vibrate, their yield is not high and they generate troublesome noises.
Another type of ultrasonic transducer is submersible, consisting of stainless steel sealed boxes, with the transducers glued inside, which, not being in contact with the vat, generate less noise and have fewer losses, but present the disadvantage of being bulky, expensive and requiring many transducers to work at high powers.
Another variant of known submersible transducers is that of tubular type, making a pipe vibrate in the liquid.
One type of such tubular transducer compresses and expands a pipe on exciting it by means of an electromechanical transducer placed at one end and a matching pad at the other.
During its operation, it is sought to tune it so that the end presenting the transducer does not vibrate, since that energy is not used in washing, but this is not satisfactorily accomplished and one does not obtain a very low impedance in phase with resonance.
The matching pad of the motor vibrates in an air cavity, the latter not being taken advantage of, and the dissipation of heat occurs basically through the pad in contact with the pipe, so that the heat is not well extracted.
The pad at the end of the pipe does not produce the same level of cavitation as the pipe through which useful volume and radiant area are lost.
The motor being contained within a pipe of greater diameter and weakly coupled, of "sonotrodo" type, radiation is not produced in that space, so that its capacity is not taken advantage of fully.
When a vat is constructed, it is sought to take maximum advantage of the volume of liquid and, for that purpose, it is necessary for the pieces to be washed to be put face to face as much as possible with radiant surfaces, for which reason efficiency and greater power handling capacity are lost with this type of tubular transducer.
Another known type is the so-called push-pull, in which the pipe is compressed and expanded between two motors of "sonotrodo" type like the previous one, which is disclosed in U.S. Pat. No. 5,200,666 of Walter et al.
This configuration radiates minimum energy longitudinally, but necessitates double the transducers and the problem persists of matching pads not taken advantage of, dissipation of heat on only one face of the transducer and the problem persists of matching pads not taken advantage of, dissipation of heat on only one face of the transducer and the fact that the transducers occupy considerable space at the ends.